The study of genetic basis of learning and memory can best be accomplished using an organism where a ready supply of genetically marked stocks are available. Drosophila meets all the requirements of a model genetic system, but to date only a few studies have demonstrated learning unequivocally. We have shown that females of this genus modify their mating choices on the basis of an earlier copulatory experience and that cycloheximide (CXM) can obliterate its expression. We are requesting funds to study the effects of CXM on this behavioral modification. The apparent "amensia" produced by this protein synthesis inhibitor may be due to its disruption of memory or it may be due to side effects of the drug such as: 1) effect of CXM on viability of sperm which the female stores after copulation; 2) the effect of illness induced by CXM; 3) altered neural input in the females; 4) altered activity levels; or 5) chemical change in pheromones released by the experienced females. It is necessary to exclude these possible effects of the drug before we can begin further work on the genetic and physiological bases of learning and memory.